1. Field of the Invention
The present invention relates to an optical writing device used in an image forming apparatus.
2. Description of the Related Art
An optical writing device is used in image forming apparatuses, such as digital copying machines and laser printers, and optical printing devices, to form a latent image on an image carrying member. Because laser printers and digital copying machines that can produce high-quality images, operate at high speed, occupy less space, are able to contribute to energy conservation, and have low manufacturing costs etc. are in demand, it is preferable that optical systems used in optical writing device of such laser printers and digital copying machines have high performance and low costs.
Costs can be reduced by reducing the number of components. Another approach to reduce the costs is to fix optical elements (lens, mirror etc.) to a housing using an adhesive, i.e., without using dedicated fixing component.
Japanese Patent Application Laid-open No. 2005-091714 discloses an optical writing device in which a component that blocks unwanted light produced because of the adhesive layer of a collimating lens is arranged in a lens holder that is located immediately after the collimating lens.
In existing technologies, a divergent laser beam emitted by a semiconductor laser is collimated by using a collimating lens. If the collimating lens is smaller, the laser beam immerging from near a periphery of the lens gets mixed with a main laser beam and it cannot be separated in a light path beyond the collimating lens. If the laser beam immerging from near the periphery of the lens gets mixed with the main laser beam, a ghost image can occur.